File extension shows in BASH but on in Finder

I created a text file with a specific extension:

Vendor_0408_Product_3008.idc

It displays in finder link this:

and BASH like this:

-rw-r--r--@  1 raven  staff    1903 Feb 19 10:31 Vendor_0408_Product_3008.idc.rtf

with a .rtf extension. In Finder, I went to preferences/advanced and made sure that "Show all filename extensions" is checked:

But it still does not display the extension?!

Please advise.